Theory of Operation
68-4004214-01 Rev D
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Establish IP Connectivity
After completing the ranging and automatic adjustments stage, the cable modem
gateway attempts to establish Internet Protocol (IP) connectivity. In this stage, the
cable modem gateway obtains network connection information and a cable modem
gateway IP address from provisioning servers that are located on the network side of
the CMTS interface.
The cable modem gateway achieves this connectivity using a protocol called
Dynamic Host Configuration Protocol (DHCP).
Note:
If the cable modem gateway fails to establish IP connectivity, it terminates the
session and restarts the initialization process at the scan for downstream channel
stage.
Establish Time of Day
After the cable modem gateway establishes IP connectivity, the cable modem
gateway requests the time of day from the network interface. This stage allows the
cable modem gateway to know the system time so that when the cable modem
gateway logs an event, it associates a time with that event.
Note:
The cable modem gateway can operate
without
establishing the time of day;
however, it logs the failure, generates an alert to simple network management
protocol (SNMP), and then proceeds to the next stage. The cable modem gateway
periodically repeats this stage to attempt to establish the time of day.
Transfer Operational Parameters
After the cable modem gateway requests the time of day, the cable modem gateway
then requests the transfer of the cable modem gateway configuration file. The cable
modem gateway makes the request to the Trivial File Transfer Protocol (TFTP)
server. The configuration file contains parameters for how the system operator
wants the cable modem gateway to function on the cable network.
Typical operation parameters for the cable modem gateway include:
Upstream and downstream rate limits
Specific frequencies
Number of CPE devices
IP filters
Port filters
MAC/LLC filters
Vendor-specific settings
Software version installed
